Science Advisory Report 2017/012
An assessment of Northern Shrimp (Pandalus borealis) in Shrimp Fishing Areas 4–6 and of Striped Shrimp (Pandalus montagui) in Shrimp Fishing Area 4 in 2016
- Resource status of Northern Shrimp in Shrimp Fishing Areas (SFAs) 5 and 6 was assessed based on Fisheries and Oceans Canada (DFO) fall multi-species trawl survey data (1996–2016). Resource status for Northern Shrimp and Striped Shrimp in SFA 4 was updated based on Northern Shrimp Research Foundation (NSRF)-DFO summer trawl survey data (2005–16).
- Trawl survey data for SFAs 4–6 provided information on shrimp distribution, length frequencies, and biomass. Trends in fisheries performance were inferred from total allowable catch (TAC), commercial catch to date, fishery catch per unit effort (CPUE) and fishing patterns.
Environment and Ecosystem (SFA 6 and Southern SFA 5)
- The regional Composite Climate Index recovered in 2016 to above 1981–2010 average (normal) conditions after declining for several years in a row to among the lowest in the time series.
- Fall bottom temperatures were above normal in 2016, resulting in above normal areas of potential thermal (2 °C to 4 °C) habitat.
- Consistent with below normal sea ice extent, the phytoplankton bloom in 2016 was earlier than in the past three years. This could lead to a further reduction in shrimp productivity in the short term.
- Environmental forcing, predation and fishing are correlated with subsequent shrimp production. The build-up of shrimp until the mid-2000s occurred during a period of favourable environmental conditions and reduced predation.
- Shrimp per-capita production has declined since the mid-2000s. Environmental conditions and increasing predation pressure appear as important drivers for the decline. Recent environmental conditions may lead to improved shrimp per-capita production but are unlikely to trigger rebuilding of the resource in SFA 6 (at a rate similar to the build-up period) over the medium term when considered in combination with high predation pressure.
- Shrimp is an important forage species, particularly when there is scarcity of high energy prey such as capelin. Shrimp predation mortality in the near future is expected to remain high unless abundance of alternative prey increases.
- Given declining production of shrimp, fishing pressure could now be influencing stock declines in SFA 6 more than it did in the past.
SFA 6 Pandalus borealis
- TAC was reduced by 42%, to 27,825 t, from 2015/16 to 2016/17; however, it is uncertain if the TAC will be fully taken.
- The annual commercial CPUE has demonstrated a declining trend for about the last ten years.
- Commercial and survey data demonstrate a contraction of the resource within recent years.
- Fishable biomass index declined from 785,000 t in 2006 to 104,000 t in 2016, which is the lowest in the time series. There was a 25% decline between 2015 and 2016.
- Female spawning stock biomass (SSB) index declined from 466,000 t in 2006 to 65,000 t in 2016 which is the lowest in the time series. There was a 27% decline between 2015 and 2016.
- The exploitation rate index ranged between 5.5% and 21.4% from 1997 to 2016/17, and has averaged 17.8% in the last five years. The 2016/17 exploitation rate index will be 20.2% if the TAC is taken.
- The female SSB index is currently in the Critical Zone, of the Integrated Fisheries Management Plan (IFMP) Precautionary Approach (PA) Framework, with greater than 99% probability. If the 27,825 t TAC is maintained and taken in the 2017/18 season, the exploitation rate index will be 26.8%.
- The IFMP states that the exploitation rate should not exceed 10% while the female SSB index is in the Critical Zone.
SFA 5 Pandalus borealis
- TAC was increased by 10%, to 25,630 t, from 2015/16 to 2016/17.
- Standardized large-vessel CPUE over the last five years has been stable at relatively high levels.
- Fishable biomass index has decreased, by 27%, from 149,000 t in 2015 to 110,000 t in 2016.
- Female SSB index has decreased, by 35%, from 83,200 t in 2015 to 54,300 t in 2016.
- The exploitation rate index has varied without trend around 15% from 1997–2016/17.
- Female SSB index is in the Healthy Zone within the IFMP PA Framework, with a 6% chance of being in the Cautious Zone. If the 25,630 t TAC is maintained and taken in 2017/18, then the exploitation rate index will be 23.3%.
SFA 4 Pandalus borealis
- TAC has remained the same, at 14,971 t, since 2013/14.
- Large-vessel standardized CPUE fluctuated without trend near the long‑term mean.
- Between 2005 and 2012 the fishable biomass index ranged between 76,600 t and 164,000 t and in 2016 was 95,300 t.
- Between 2005 and 2012 the female SSB index ranged between 39,700 t and 115,000 t and in 2016 was 55,500 t.
- The exploitation rate index has been about 15% for the past three years.
- Female SSB index in 2016 was in the Healthy Zone within the IFMP PA Framework with a 45% probability of having been in the Cautious Zone.
SFA 4 Pandalus montagui
- Commercial catch of P. montagui, taken as by-catch in the P. borealis fishery, increased from 280 t in 2008 to 4,700 t in 2012 and declined to 1,092 t in 2016. The by-catch limit of 4,033 t has not been taken in the past four years.
- Fishable biomass index for 2016 was 23,900 t, a decrease of 49% from 2015.
- Female SSB is unknown.
- If the by-catch limit had been taken, the exploitation rate would have been 8.7% in 2016/17.
- There is no IFMP PA Framework for this resource.
This Science Advisory Report is from the February 16–17, 2017 Northern and Striped Shrimp Assessment. Additional publications from this meeting will be posted on the DFO Science Advisory Schedule as they become available.
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